Local heat treatment system and cold forming method using the same

ABSTRACT

The present disclosure relates to a local heat treatment system and a cold forming method using the same. The local heat treatment system includes a heating device configured to locally heat only a plastic deformation occurrence portion of a blank material to a predetermined temperature, a moving device configured to move the heating device to a position of a local heating region of the blank material, and a controller configured to control the heating device and the moving device.

TECHNICAL FIELD

The present disclosure relates to a local heat treatment system and acold forming method using the same, and more particularly, to a localheat treatment system and a cold forming method using the same capableof improving the formability of an ultra-high tensile steel sheet andminimizing the springback phenomenon.

BACKGROUND ART

In general, weight reduction of automobiles is effective for improvingautomobile fuel economy, and thus, the use of a high-tensile steelsheet, which is a material having a high specific strength, isincreasing in recent years. The strength of such a high-tensile steelsheet is improving, and in recent years, an ultra-high tensile steelsheet having a tensile strength of 1 GPa or more has also beendeveloped.

Because the ultra-high tensile steel sheet has a high strength, pressmolding of the ultra-high tensile steel sheet is not easy, so that it iseasy to cause seizing due to increased molding load and increased moldwear, and the springback at which the molded shape returns is large, andthus the shape fixability is deteriorated. In addition, the ultra-hightensile steel sheet has a low ductility and tends to crack when atensile stress is applied during molding.

Therefore, in order to improve the formability of the ultra-high tensilesteel sheet, which is a difficult-to-form material, and to reduce thespringback phenomenon, methods of improving formability by heating theentire molding material have been developed. As an example, a method ofimproving formability by heating the entire material, such as a warmforming process, has been applied. However, this method of heating theentire difficult-to-form material may cause unnecessary energy loss byheating even a region where molding is not performed.

Due to the above-described problem, a method of molding by locallyheating only a part requiring plastic deformation through a laser ornear-infrared heating device has been proposed and used. However,because this method is to warm a material after heating the material ina warm forming process, the productivity due to the heating timedecreases, and during material handling, the local heating part coolsquickly, making it difficult to maintain a constant quality.

Accordingly, there is a growing demand for a method and apparatus thatdoes not heat the material in the molding process and thus does notdecrease productivity, and performs cold forming rather than warmforming in order to secure a certain quality.

DISCLOSURE Technical Problem

The present disclosure is directed to providing a local heat treatmentsystem and a cold forming method using the same capable of improvingformability by locally heating a part to be plastically deformed throughan external heat source and then cooling the part to adjust physicalproperties.

The present disclosure is directed to providing a local heat treatmentsystem and a cold forming method using the same capable of improvingproductivity as well as reducing springback by cold forming a materialwhose physical properties are adjusted.

Technical Solution

An aspect of the present disclosure provides a local heat treatmentsystem including a heating device configured to locally heat only aplastic deformation occurrence portion of a blank material to apredetermined temperature, a moving device configured to move theheating device to a position of a local heating region of the blankmaterial, and a controller configured to control the heating device andthe moving device.

The heating device may include a housing coupled to the moving device, aheat source coupled to the housing to emit near-infrared rays, and areflector provided in the housing to condense light into the localheating region by reflecting the near-infrared rays generated by theheat source.

The moving device may include a rotating joint coupled to the heatingdevice, and a plurality of moving members coupled to the rotating jointto move the heating device in three axes (x, y, and z) directions.

The plurality of moving members may include a first moving membercoupled to the rotating joint to move the heating device in a directionin which the blank material is disposed, a second moving member coupledto the first moving member to move the first moving member in a verticaldirection, and a third moving member coupled to the second moving memberto move the second moving member in a horizontal direction.

The moving device and the heating device may be provided as onesub-assembly, a plurality of the sub-assemblies may be provided tolocally heat the blank material on one side and the other side of theblank material, respectively, and the sub-assemblies may beindependently controlled by the controller.

The controller may control the moving device and the heating device bysetting a local heating position, a heating temperature, and a heatingtime in consideration of a strain and stress depending on a shape to bemolded in a forming process of the blank material.

Another aspect of the present disclosure provides a cold forming methodusing the local heat treatment system according to any one of claims 1to 6, which includes (a) operating the moving device so that the heatingdevice is located in the local heating region, which is the plasticdeformation occurrence portion, when the blank material is introducedinto the local heat treatment system, (b) locally adjusting the physicalproperties of the blank material by heating and then cooling the plasticdeformation occurrence portion of the blank material through the heatingdevice to a predetermined temperature when the heating device is locatedin the local heating region, and (c) performing cold forming aftermoving the blank material whose physical properties is adjusted to amold.

In process (a), the controller of the local heat treatment system maycontrol the moving device and the heating device by setting a localheating position, a heating temperature, and a heating time inconsideration of a strain and stress depending on a shape to be moldedin a forming process of the blank material.

Advantageous Effects

A local heat treatment system according to an embodiment of the presentdisclosure and a cold forming method using the same can improveformability of a material by selectively heating the material locallyusing an external heat source and then cooling the material to adjustphysical properties thereof.

Further, by locally heating only a part to be plastically deformed sothat the physical properties are adjusted, a molding load can bereduced, so that the wear of the mold can be minimized during coldforming and springback phenomenon can be minimized after the coldforming.

Further, compared to conventional hot forming, productivity and qualitycan be improved, as well as energy cost can be reduced.

Further, as artificial intelligence (AI) and sensing technology arecombined, the process can be easily and quickly performed when thematerial is locally heated, thereby improving productivity, and thelocal heat treatment system can be conveniently applied even when thematerial has a complex molding shape

DESCRIPTION OF DRAWINGS

FIG. 1 is a view schematically illustrating a local heat treatmentsystem according to an embodiment of the present disclosure.

FIG. 2 is a view showing a state in which the local heat treatmentsystem according to an embodiment of the present disclosure is inoperation.

FIG. 3 is a perspective view showing in detail a moving device of thelocal heat treatment system shown in FIG. 2.

FIG. 4 is a view showing a heating device provided in the local heattreatment system according to an embodiment of the present disclosure.

FIG. 5 is a view showing irradiation of a heat source depending on ashape of a reflector provided in the heating device shown in FIG. 4.

FIG. 6 is a view taken to compare a state of V-bending molding of amaterial whose physical properties are adjusted by the local heattreatment system according to an embodiment of the present disclosureand a state of V-bending molding of a conventional material.

FIG. 7 is a view taken to compare a material whose physical propertiesare adjusted by the local heat treatment system according to anembodiment of the present disclosure and a conventional material that isasymmetrically molded.

FIG. 8 is a view taken to compare an actual part whose physicalproperties are adjusted by the local heat treatment system according toan embodiment of the present disclosure and a conventional actual partthat is molded.

MODE OF THE DISCLOSURE

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the accompanying drawings. The followingembodiments are provided to fully convey the spirit of the presentdisclosure to a person having ordinary skill in the art to which thepresent disclosure belongs. The present disclosure is not limited to theembodiments shown herein but may be embodied in other forms. Thedrawings are not intended to limit the scope of the present disclosurein any way, and the size of components may be exaggerated for clarity ofillustration.

FIG. 1 is a view schematically illustrating a local heat treatmentsystem according to an embodiment of the present disclosure, FIG. 2 is aview showing a state in which the local heat treatment system accordingto an embodiment of the present disclosure is in operation, FIG. 3 is aperspective view showing in detail a moving device of the local heattreatment system shown in FIG. 2, FIG. 4 is a view showing a heatingdevice provided in the local heat treatment system according to anembodiment of the present disclosure, and FIG. 5 is a view showingirradiation of a heat source depending on a shape of a reflectorprovided in the heating device shown in FIG. 4.

Referring to FIGS. 1 to 5, a local heat treatment system 1 according toan embodiment of the present disclosure includes a heating device 100 toheat only a part in which plastic deformation of a blank material 10 isgenerated, a moving device 200 to move the heating device 100 to aposition of a local heating region of the blank material 10, and acontroller 300 to control the heating device 100 and the moving device200.

The blank material 10 is a difficult-to-form material having a tensilestrength of 1 GPa or more, which is an ultra-high tensile steel materialthat is cut to have a predetermined length in order to form a productthrough cold forming according to the present disclosure. Because aregion in which an actual plastic deformation is generated in a processof producing the blank material 10 as a product is local, formability ofthe blank material 10 may be improved by applying heat only to a regionin which plastic deformation is generated using a separate external heatsource. That is, in order to improve the formability of the material, itis important to focus a location where heat is applied to only a localregion in which the plastic deformation of the blank material 10 isgenerated.

When bending molding of the blank material 10 is performed, it is moreefficient that a near-infrared heat source is used as an external heatsource than in other processes. In addition, because most of the bendingmolding is linear, it is appropriate to use a linear heat source.

Therefore, in the present disclosure, the heating device 100 is used asan external heat source, and a temperature of a local region in whichplastic deformation is generated is increased by using a linearnear-infrared heater, so that the bending properties of adifficult-to-form material may be improved, thereby molding the materialinto a precise shape.

More specifically, as shown in FIG. 4, the heating device 100 includes aheat source 110 and a reflector 120. The heat source 110 may be providedas a lamp that generates near-infrared rays.

The heat source 110 is an electromagnetic wave having a wavelength of700 to 1300 nm and is generated outside of a visible red light. Because90% or more of the heat source 110 is radiant heat, the efficiency ofthe heat source 110 may be high (85% to 90% efficiency). Because theheat source 110 is near-infrared rays and thus does not burn air, theheat source 110 which is non-toxic, smokeless, odorless, and noiselessmay be used indoors. The heat source 110 is very convenient to usebecause it only takes about 0.1 seconds to reach a maximum output.

The reflector 120 serves to reflect near-infrared rays generated fromthe heat source and condense light into the local heating region. Thereflector 120 may linearly adjust a region to which near-infrared raysare irradiated according to a shape. For example, FIG. 5A shows thereflector 120 formed in an elliptical shape, and FIG. 5B shows thereflector 120 formed in a parabolic shape. In the case of the ellipticalreflector 120, near-infrared rays generated from the heat source 110 arereflected and condensed to one point to be linearly irradiated to theblank material 10. In the case of the parabolic reflector 120,near-infrared rays generated from the heat source 110 are parallelizedto be irradiated onto a predetermined region of the blank material 10.That is, depending on a plastic deformation region of the blank material10, the reflector 120 suitable for that region may be applied to belocally heated. In addition, reflectors of various shapes may beprovided to be utilized according to respective characteristics thereof.Therefore, depending on the purpose, the shape of the reflector 120 maybe modified and used.

As described above, because the heating device 100 using near-infraredrays uses only the heat source 110 and the reflector 120, the blankmaterial 10 may be locally heated from one direction.

The heating device 100 may further include a housing 130. The housing130 serves to protect the heat source 110 and the reflector 120 fromexternal impacts and prevent energy loss through heat insulation. Thehousing 130 is provided such that the heat source 110 and the reflector120 are coupled, and a part of the housing 130 has an open shape so thatnear-infrared rays generated from the heat source 110 are irradiated inone direction through the reflector 120. In addition, the housing 130may be coupled to the moving device 200, which will be described later.

The moving device 200 serves to move the heating device 100 to a surfaceof a region of the blank material 10 to be plastically deformed, bybeing combined with the heating device 100. The moving device 200includes a rotating joint 213 coupled to the heating device 100 and aplurality of moving members 210, 220, and 230 to move the heating device100 in three axial directions.

The rotating joint 213 is coupled to the housing 130 of the heatingdevice 100 to adjust an angle of the heating device 100. That is, therotating joint 213 serves to adjust the angle of the heating device 100so that near-infrared rays may be smoothly condensed on the surface ofthe local heating region of the blank material 10. The structure of therotating joint 213 is a generally well-known technique, and thus adetailed description thereof will be omitted.

The plurality of moving members 210, 220, and 230 is composed of thefirst moving member 210, the second moving member 220, and the thirdmoving member 230 in order to move the heating device 100 in three axialdirections, that is, in x, y, and z-axis directions. For example, asshown in FIG. 3, the third moving member 230 may be provided to move inthe x-axis direction, the second moving member 220 may be provided tomove in the y-axis direction, and the first moving member 210 may beprovided to move in the z-axis direction.

The first moving member 210 is coupled to the rotating joint 213 to movethe heating device 100 in a direction in which the blank material 10 isdisposed, that is, in the z-axis direction. The first moving member 210may be provided with a hydraulic or pneumatic cylinder to move in onedirection.

The second moving member 220 is coupled with the first moving member 210to move the first moving member 210 in a vertical direction, that is, inthe y-axis direction. Because the first moving member 210 is coupled tothe heating device 100, the heating device 100 is moved together whenthe first moving member 210 moves. The second moving member 220 may beprovided with a hydraulic or pneumatic cylinder to move in onedirection.

The third moving member 230 is coupled with the second moving member 220to move the second moving member 220 in a horizontal direction, that is,in the x-axis direction. Because the second moving member 220 coupled tothe first moving member 210, the first moving member 210 is movedtogether when the second moving member 220 moves. The third movingmember 230 may have a coupling structure of rack and pinion gears thatreceive a rotational force of a motor 232 and convert the rotationalforce into a linear motion.

The present embodiment illustrates that the first and second movingmembers 210 and 220 have a cylinder structure and the third movingmember 230 has a gear coupling structure that converts a rotationalmotion into a linear motion, but the present disclosure Is not limitedthereto, and the moving members may have various structures as long asthe heating device 100 may be moved in three axial directions.

The local heat treatment system 1 according to an embodiment of thepresent disclosure may be configured such that the moving device 200 andthe heating device 100 form one sub-assembly, and a plurality of thesub-assemblies may be provided to locally heat the blank material 10 atrequired positions on one side and the other side of the blank material10, respectively. The plurality of sub-assemblies may be independentlycontrolled by the controller 300.

The controller 300 may control independently the plurality ofsub-assemblies as described above, respectively, as well as control theheating device 100 and the moving device 200, respectively. Thecontroller 300 may be combined with artificial intelligence (AI) andsensing technology to more efficiently control each of thesub-assemblies. For example, the controller 300 may measure a strain andstress during the molding process, which are the molding characteristicsof an object to be molded before the blank material 10 is locally heatedand may optimize a local heating position, a heating temperature, aheating time, and the like in consideration of a molding shape, aprocess time, and the like. That is, the controller 300 may control themoving device 200 and the heating device 100 by setting the localheating position, the heating temperature, and the heating time based onmeasurement data obtained by measuring the object to be molded.Accordingly, when the blank material 10 is located in the local heattreatment system 1, the moving device 200 is operated to quickly andeasily move the heating device 100 to an optimized point, and theheating device 100 heats the heating position by time and at a constanttemperature. Therefore, the local heat treatment system 1 may beconveniently applied even when the object to be molded has a complexmolding shape, and at the same time may be applied to various shapes.

Hereinafter, a method of cold forming the blank material 10 using thelocal heat treatment system 1 as described above will be described withreference to FIGS. 1 to 5.

The cold forming method of the present disclosure largely includes aprocess of locally heating and then cooling a plastic deformationgenerating part of the blank material 10 through the local heattreatment system 1, and a process of positioning the locally heatedblank material 10 into a mold and then molding the blank material 10.

Specifically, as shown in FIG. 1, when the blank material 10 isintroduced into the local heat treatment system 1, the moving device 200is operated such that the heating device 100 is located in a localheating region, which is a region in which plastic deformation isgenerated. That is, as shown in FIG. 2, when the heating device 100 islocated in the local heating region, the plastic deformation generatingpart of the blank material 10 is heated to a predetermined temperaturethrough the heating device 100. The locally heated blank material 10goes through a cooling process so that physical properties of thematerial are adjusted and then is provided for a cold forming process.That is, by adjusting the physical properties of the blank material 10in advance prior to the cold forming process, a forming process time maybe shortened compared to a conventional process of performing warmforming after heating a material in a warm forming process.

The heating device 100 and the moving device 200 may be controlled bythe controller 300 to locally heat the blank material 10. The controller300 independently controls the plurality of heating devices 100 andmoving devices 200, respectively. The controller 300 may control themoving device 200 and the heating device 100 by setting a local heatingposition, a heating temperature, and a heating time in consideration ofthe strain and stress depending on a shape to be molded during themolding process of the blank material 10.

For example, the controller 300 may be combined with artificialintelligence (AI) and sensing technology to more efficiently control themoving device 200 and the heating device 100. That is, the controller300 may measure a strain and stress during the molding process, whichare the molding characteristics of an object to be molded before theblank material 10 is locally heated and may optimize a local heatingposition, a heating temperature, a heating time, and the like inconsideration of a molding shape, a process time, and the like.Accordingly, the controller 300 may control the moving device 200 andthe heating device 100 by setting the local heating position, theheating temperature, and the heating time based on measurement dataobtained by measuring the object to be molded. Therefore, when the blankmaterial 10 is located in the local heat treatment system 1, the movingdevice 200 is operated to quickly and easily move the heating device 100to an optimized point, and the heating device 100 heats the heatingposition by time and at a constant temperature.

The blank material 10 introduced into the local heat treatment system 1may be fixed at a predetermined position through a separate holder (notshown). That is, the blank material 10 may be supported by the holder soas not to interfere with a part heated through the heating device 100.

The blank material 10 locally heated through the local heat treatmentsystem 1 is provided in a state in which the physical properties of thematerial are adjusted by being cooled.

Thereafter, the blank material 10 whose physical properties are adjustedis molded to have a required shape through cold forming.

Hereinafter, the present disclosure will be described in more detailthrough embodiments 1 to 6 and comparative examples 1 to 3.

Embodiment 1

A blank material is prepared as an ultra-high tensile steel having atensile strength of 1.5 GPa, and a part to be plastically deformed islocally heated to 550° C. and then V-shaped bending molding isperformed.

Embodiment 2

A blank material is prepared as an ultra-high tensile steel having atensile strength of 1.5 GPa, and a part to be plastically deformed islocally heated to 850° C. and then V-shaped bending molding isperformed.

Embodiment 3

A blank material is prepared as an ultra-high tensile steel having atensile strength of 1.5 GPa, and a part to be plastically deformed islocally heated to 950° C. and then V-shaped bending molding isperformed.

Embodiment 4

A blank material is prepared as an ultra-high tensile steel having atensile strength of 1.2 GPa, and a part to be plastically deformed islocally heated to 400° C. and then asymmetric molding is performed.

Embodiment 5

A blank material is prepared as an ultra-high tensile steel having atensile strength of 1.2 GPa, and a part to be plastically deformed islocally heated to 800° C. and then asymmetric molding is performed.

Embodiment 6

A blank material is prepared as an ultra-high tensile steel having atensile strength of 1.5 GPa, and a part to be plastically deformed islocally heated to 800° C. and then molding of an actual part isperformed.

Comparative Example 1

A blank material is prepared as an ultra-high tensile steel having atensile strength of 1.5 GPa, and V-shaped bending molding is performedwithout local heating.

Comparative Example 2

A blank material is prepared as an ultra-high tensile steel having atensile strength of 1.2 GPa, and asymmetric molding is performed withoutlocal heating.

Comparative Example 3

A blank material is prepared as an ultra-high tensile steel having atensile strength of 1.5 GPa, and molding of an actual part is performedwithout local heating.

TABLE 1 Embodiments/ Type of Comparative Molding Local Molding SteelExamples Methods Heating Results 1.5 GPa Embodiment 1 V-shaped bending550° C. No cracks ultra- molding high Embodiment 2 V-shaped bending 850°C. No cracks tensile molding steel Embodiment 3 V-shaped bending 950° C.No cracks molding 1.2 GPa Embodiment 4 Asymmetric 400° C. Springbackultra- molding 15° high Embodiment 5 Asymmetric 800° C. Springbacktensile molding  7° steel 1.5 GPa Embodiment 6 Molding of an 800° C. Nocracks ultra- actual part high tensile steel 1.5 GPa ComparativeV-shaped bending — Crack ultra- Example 1 molding occurrence hightensile steel 1.2 GPa Comparative Asymmetric — Springback ultra- Example2 molding 25° high tensile steel 1.5 GPa Comparative Molding of an —Crack ultra- Example 3 actual part occurrence high tensile steel

As may be seen from the molding results in [Table 1], no cracks occurredas a result of molding after performing local heating, and thespringback phenomenon was significantly reduced. Results according tothe experiments of these embodiments and comparative examples are shownin FIGS. 6 to 8.

FIG. 6 is a view taken to compare a state of V-bending molding of amaterial whose physical properties are adjusted by the local heattreatment system according to an embodiment of the present disclosureand a state of V-bending molding of a conventional material.

FIG. 6A shows a state in which V-bending molding is performed throughComparative example 1, and FIG. 6B shows a state in which V-bendingmolding is performed through Embodiments 1 to 3. That is, as shown inthe drawing, in the case of Comparative example 1, it may be confirmedthat a crack occurred in the plastically deformed part. In contrast, inthe case of Embodiments 1 to 3 of the present disclosure, because thephysical properties were adjusted by locally heating a part to beplastically deformed, the part was smoothly molded without cracking.

FIG. 7 is a view taken to compare a material whose physical propertiesare adjusted by the local heat treatment system according to anembodiment of the present disclosure and a conventional material that isasymmetrically molded.

FIG. 7A shows a state in which asymmetric molding is performed throughComparative example 2, and FIG. 7B shows a state in which asymmetricmolding is performed through Embodiment 4. That is, as shown in thedrawing, in the case of Comparative example 2, it may be confirmed thata 25° springback phenomenon occurred after asymmetric molding. Incontrast, in the case of Embodiment 5 of the present disclosure, becausethe physical properties were adjusted by locally heating a part to beplastically deformed, no cracking occurred, and a 7° springbackphenomenon occurred. That is, it may be seen that the springback issignificantly reduced compared to the prior art.

FIG. 8 is a view taken to compare an actual part whose physicalproperties are adjusted by the local heat treatment system according toan embodiment of the present disclosure and a conventional actual partthat is molded.

FIG. 8A shows a state in which an actual part is molded throughComparative example 3, and FIG. 8B shows a state in which an actual partis molded through Embodiment 6. That is, as shown in the drawing, in thecase of Comparative example 3, it may be confirmed that cracks andfractures occurred in the plastically deformed part. In contrast, in thecase of Embodiment 6 of the present disclosure, because the physicalproperties were adjusted by locally heating a part to be plasticallydeformed, the part was molded without cracks and fractures.

It may be confirmed from FIG. 8B that the physical properties wereadjusted by not wholly heating a portion where the actual part isplastically deformed, but by locally heating opposite ends, that is,portions where cracks and fractures occurred during plastic deformationof the existing real part, and then cooling the portions. This isdetermined by the data values obtained by measuring a strain and stressduring the molding process in consideration of the moldingcharacteristics of an object to be molded. Therefore, because all partsto be plastically deformed may be prevented from being unnecessarilylocally heated, not only may the waste of energy be more effectivelyreduced, but also productivity may be improved. In addition, anoptimized heating position may be set, and a heating time and a heatingtemperature may be provided. That is, the local heat treatment system 1capable of improving formability and minimizing the springbackphenomenon, and the cold forming method through the same may beprovided, and a molded part with improved quality may be provided.

The foregoing has illustrated and described specific embodiments.However, it should be understood by those of skilled in the art that thedisclosure is not limited to the above-described embodiments, andvarious changes and modifications may be made without departing from thetechnical idea of the disclosure described in the following claims.

1. A local heat treatment system comprising: a heating device configured to locally heat only a plastic deformation occurrence portion of a blank material to a predetermined temperature; a moving device configured to move the heating device to a position of a local heating region of the blank material; and a controller configured to control the heating device and the moving device.
 2. The local heat treatment system according to claim 1, wherein the heating device comprises: a housing coupled to the moving device; a heat source coupled to the housing to emit near-infrared rays; and a reflector provided in the housing to condense light into the local heating region by reflecting the near-infrared rays generated by the heat source.
 3. The local heat treatment system according to claim 1, wherein the moving device comprises: a rotating joint coupled to the heating device; and a plurality of moving members coupled to the rotating joint to move the heating device in three axes (x, y, and z) directions.
 4. The local heat treatment system according to claim 3, wherein the plurality of moving members comprises: a first moving member coupled to the rotating joint to move the heating device in a direction in which the blank material is disposed; a second moving member coupled to the first moving member to move the first moving member in a vertical direction; and a third moving member coupled to the second moving member to move the second moving member in a horizontal direction.
 5. The local heat treatment system according to claim 1, wherein the moving device and the heating device are provided as one sub-assembly, a plurality of the sub-assemblies is provided to locally heat the blank material on one side and the other side of the blank material, respectively, and the sub-assemblies are independently controlled by the controller.
 6. The local heat treatment system according to claim 1, wherein the controller controls the moving device and the heating device by setting a local heating position, a heating temperature, and a heating time in consideration of a strain and stress depending on a shape to be molded in a forming process of the blank material.
 7. A cold forming method using the local heat treatment system according to claim 1, comprising: (a) operating the moving device so that the heating device is located in the local heating region, which is the plastic deformation occurrence portion, when the blank material is introduced into the local heat treatment system; (b) locally adjusting the physical properties of the blank material by heating and then cooling the plastic deformation occurrence portion of the blank material through the heating device to a predetermined temperature when the heating device is located in the local heating region; and (c) performing cold forming after moving the blank material whose physical properties is adjusted to a mold.
 8. The cold forming method according to claim 7, wherein in process (a), the controller of the local heat treatment system controls the moving device and the heating device by setting a local heating position, a heating temperature, and a heating time in consideration of a strain and stress depending on a shape to be molded in a forming process of the blank material. 